BPF ring buffer

Implement a new BPF ring buffer, as presented at BPF virtual conference ([0]).
It presents an alternative to perf buffer, following its semantics closely,
but allowing sharing same instance of ring buffer across multiple CPUs
efficiently.

Most patches have extensive commentary explaining various aspects, so I'll
keep cover letter short. Overall structure of the patch set:
- patch #1 adds BPF ring buffer implementation to kernel and necessary
  verifier support;
- patch #2 adds litmus tests validating all the memory orderings and locking
  is correct;
- patch #3 is an optional patch that generalizes verifier's reference tracking
  machinery to capture type of reference;
- patch #4 adds libbpf consumer implementation for BPF ringbuf;
- path #5 adds selftest, both for single BPF ring buf use case, as well as
  using it with array/hash of maps;
- patch #6 adds extensive benchmarks and provide some analysis in commit
  message, it build upon selftests/bpf's bench runner.

  [0] https://docs.google.com/presentation/d/18ITdg77Bj6YDOH2Lg...

Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Jonathan Lemon <jonathan.lemon@gmail.com>

Andrii Nakryiko (6):
  bpf: implement BPF ring buffer and verifier support for it
  tools/memory-model: add BPF ringbuf MPSC litmus tests
  bpf: track reference type in verifier
  libbpf: add BPF ring buffer support
  selftests/bpf: add BPF ringbuf selftests
  bpf: add BPF ringbuf and perf buffer benchmarks

 include/linux/bpf.h                           |  12 +
 include/linux/bpf_types.h                     |   1 +
 include/linux/bpf_verifier.h                  |  12 +
 include/uapi/linux/bpf.h                      |  33 +-
 kernel/bpf/Makefile                           |   2 +-
 kernel/bpf/helpers.c                          |   8 +
 kernel/bpf/ringbuf.c                          | 409 ++++++++++++
 kernel/bpf/syscall.c                          |  12 +
 kernel/bpf/verifier.c                         | 252 ++++++--
 kernel/trace/bpf_trace.c                      |   8 +
 tools/include/uapi/linux/bpf.h                |  33 +-
 tools/lib/bpf/Build                           |   2 +-
 tools/lib/bpf/libbpf.h                        |  20 +
 tools/lib/bpf/libbpf.map                      |   4 +
 tools/lib/bpf/libbpf_probes.c                 |   5 +
 tools/lib/bpf/ringbuf.c                       | 264 ++++++++
 .../litmus-tests/mpsc-rb+1p1c+bounded.litmus  |  92 +++
 .../litmus-tests/mpsc-rb+1p1c+unbound.litmus  |  83 +++
 .../litmus-tests/mpsc-rb+2p1c+bounded.litmus  | 152 +++++
 .../litmus-tests/mpsc-rb+2p1c+unbound.litmus  | 137 ++++
 tools/testing/selftests/bpf/Makefile          |   5 +-
 tools/testing/selftests/bpf/bench.c           |  18 +
 .../selftests/bpf/benchs/bench_ringbufs.c     | 593 ++++++++++++++++++
 .../bpf/benchs/run_bench_ringbufs.sh          |  61 ++
 .../selftests/bpf/prog_tests/ringbuf.c        | 101 +++
 .../selftests/bpf/prog_tests/ringbuf_multi.c  | 102 +++
 .../selftests/bpf/progs/perfbuf_bench.c       |  33 +
 .../selftests/bpf/progs/ringbuf_bench.c       |  45 ++
 .../selftests/bpf/progs/test_ringbuf.c        |  63 ++
 .../selftests/bpf/progs/test_ringbuf_multi.c  |  77 +++
 30 files changed, 2584 insertions(+), 55 deletions(-)
 create mode 100644 kernel/bpf/ringbuf.c
 create mode 100644 tools/lib/bpf/ringbuf.c
 create mode 100644 tools/memory-model/litmus-tests/mpsc-rb+1p1c+bounded.litmus
 create mode 100644 tools/memory-model/litmus-tests/mpsc-rb+1p1c+unbound.litmus
 create mode 100644 tools/memory-model/litmus-tests/mpsc-rb+2p1c+bounded.litmus
 create mode 100644 tools/memory-model/litmus-tests/mpsc-rb+2p1c+unbound.litmus
 create mode 100644 tools/testing/selftests/bpf/benchs/bench_ringbufs.c
 create mode 100755 tools/testing/selftests/bpf/benchs/run_bench_ringbufs.sh
 create mode 100644 tools/testing/selftests/bpf/prog_tests/ringbuf.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
 create mode 100644 tools/testing/selftests/bpf/progs/perfbuf_bench.c
 create mode 100644 tools/testing/selftests/bpf/progs/ringbuf_bench.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_ringbuf.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_ringbuf_multi.c

-- 
2.24.1